FREDERICKSBURG, Va. -- As the Marine Corps moves forward with its plan for a large unmanned aerial system that can take off and land from the deck of a ship, the list of things the drone needs to do in order to meet service requirements is narrowing dramatically.

The final design for the drone the Marines are calling the MUX may not be able to carry weapons, conduct logistics and resupply missions, or escort the MV-22 Osprey, officials said at an industry day near Quantico, Virginia Wednesday.

All of those mission sets have been moved to "Tier 2" or "Tier 3" requirements, and earmarked for other aircraft in planning.

On the list of Tier 1 priorities remain airborne early warning capabilities, electronic warfare, comms relay and command-and-control. In short, the MUX will be an eye-in-the-sky for the Marine Corps and a network platform to expand the reach of manned aircraft and enhance communication.

It's a significantly more modest dream than the concept Marine officials started to pitch several years ago of an unmanned aircraft that could carry the same weapons as an F-35 Joint Strike Fighter and keep up with an MV-22. But it fills a key capability gap for the Marine Corps, a service that does not have a native airborne early warning platform and is leaning into EW capabilities at every level of the fight.

"We wanted something that was going to be big, expensive and probably beyond the reach of the Marine Corps," Brig. Gen. James "Rainman" Adams, a capability development director for the MUX, said of the early plans. "[Something that could carry] thousands of pounds of cargo and fire long range missiles."

Now, he said, the Marine Corps was willing to trade those capabilities in exchange for a system that meets its most pressing needs.

Adams told an audience of industry professionals that he envisioned the MUX to be somewhere between the United Kingdom's Crowsnest carrier-based unmanned rotorcraft and the Navy's manned E-2D Advanced Hawkeye carrier-based airborne early warning aircraft in terms of capability.

Having a native airborne early warning capability and networking platform would expand possibilities for ground troops as well as aircraft, he said, increasing lethality and strengthening communications.

"If you have to hang a bunch of weapons on the MUX, you're going to limit your payload," he said. "That may not be needed if you can link into the network and shoot other peoples' weapons."

Lt. Gen. Robert Walsh, commander of Marine Corps Combat Development Command, said the Marine Corps would be working closely with the Navy in developing the MUX, stipulating that the final design had to be small enough to fit into the hangar of a guided-missile destroyer so that it could launch from surface ships as well as amphibious vessels.

"The Army would like to have this capability [too]," Walsh said. "If you project forward out into the future, you're going to see lots of these."

There are certain requirements that haven't changed. MUX needs to be able to loiter for eight hours on station and have a radius of 350 nautical miles, officials said.

And they still want to get it in the air fast.

Lt. Gen. Steven "Stick" Rudder, the Marines' head of aviation, said the service would like to see the MUX flying by the early 2020s, when multiple previous aircraft acquisition programs, including the MV-22 Osprey, the KC-130J Hercules, and the AH-1Z Viper, will be wrapping up.

Initial operational capability, officials said, is desired in 2027.

"We would like to go fast," Rudder told the industry representatives. "That's why we're here with you, to hear what you think fast is."

As far as how much money the Marines will get to execute their MUX vision, much is still unknown. Walsh pointed out that the Congress earmarked $10 million for early MUX development in its version of the still-to-be-finalized FY19 defense budget bill, while the Senate Armed Services Committee allowed a much more generous $100 million for the program. The bill is still awaiting conference to reconcile to two versions.

"You look at [MQ-9] Reapers at $16 million and [MQ-1] Predators at $22 million, It's got to be somewhere in that area," Walsh said. "We're talking in the mid to high 20s. The Navy can afford Triton; we can't afford something like that."

The MQ-4C Triton, designed for intelligence, surveillance and reconnaissance over ocean and coastal regions, had an early unit cost of $120 million.

Ultimately, officials said, the MUX corresponds to the vision set by Defense Secretary Jim Mattis in his recent national defense strategy to develop a more maritime military focus.

"The threat is driving our concepts," Walsh said. "The strategy driving the concepts comes straight from SecDef, and we think MUX is a key part of that."